1. Field of the Invention
The invention relates to interferometry-based methods and compositions useful for measuring enzyme activity.
2. Description of the Related Art
Enzymes represent a broad class of proteins that catalyze biochemical reactions and have many therapeutic and industrial applications. Often in the course of development and manufacture of enzyme products it is necessary to measure the activity of the enzyme. A simple enzyme activity method, preferably label free thereby avoiding perturbation of the enzyme/substrate interaction, would find wide application. In the development and manufacture of enzyme or enzyme inhibitor based products for therapeutic or industrial applications, it is critical to monitor the activity of the enzyme throughout the process. Enzyme assays typically require labeling the substrate in such a way that the enzyme acting on the substrate produces a detectable change in signal. Labeled enzyme substrates are often not commercially available, in which case their synthesis can be complex. For companies developing a multitude of enzyme products, the implementation of activity methods that are simple and easy to perform in research & development and manufacturing environments becomes a major task. The need for labeled substrates adds to the time, expense and inconvenience of enzyme activity measurements. Specific activity measurements also require quantifying the amount of enzyme present in a sample. Quantitation, as by, e.g., enzyme-linked immunosorbant (ELISA)-based assays are also adds to the time and expense of specific activity measurements and requires additional sample. The present invention addresses these and other shortcomings of the prior art by providing simple, fiber based, real-time enzyme activity assays, capable of providing specific activity measurements, suitable for low-volume samples, that are highly multiplexable and in some embodiments can be carried out using unlabeled substrates.